1. Field of the Invention
The present invention relates to an information processing such as image forming apparatus having a data writing function to a non-volatile memory such as an integrated circuit (IC) tag, and a method of controlling a power source of the information processing apparatus.
2. Description of the Background Art
Information processing apparatuses such as image forming apparatuses have been equipped with enhanced machine information service for maintenance service of machines and/or enhanced information providing service to machine users, by which service engineers and/or users can obtain and utilize settings information related to machines and/or use-state information of consumables. Such information can be obtained from, for example, a non-volatile memory such as an integrated circuit (IC) tag provided for each of machines as disclosed in JP-2003-224677-A.
The IC tag is generally an IC chip, which includes a memory to store information, a control circuit to read and write information for the memory, and a communication circuit to conduct wireless or wired communication with other devices. For example, the IC tag may be attached to individual toner bottles, storing color agents used for printing such as pigment-based toner, which are detachably installed in an image forming apparatus, in which data such as information of remaining toner amount can be written to and/or read from the memories of the IC tags. The memories used for the IC tags generally employ a rewritable non-volatile memory that can retain or store information even when a power supply of the IC tag is turned OFF state, and such memory may be, for example, an electrically erasable programmable read-only memory (EEPROM) or the like.
The IC tag attached to consumables such as toner bottles can be re-used in various ways. For example, an IC tag attached to a toner bottle may be re-used with the toner bottle which is refilled with fresh toner, or removed from a toner-consumed bottle and attached to a new toner bottle filled with fresh toner. However, there is an upper limit to the number of times the memory can be rewritten, because memory elements in non-volatile memories used for IC tags deteriorate by repeating the refreshing process.
In view of such drawback, the number of times that the IC tags can be re-used can be increased by decreasing the number of times data is written to the non-volatile memories in the IC tags. For example, the number of times data is written to the non-volatile memories can be decreased by writing data to the non-volatile memory only when an image forming apparatus is in a state of power OFF and/or toner replacement, that is, not updating toner information in the non-volatile memories at a given periodical timing such as when a given number of sheets are printed.
Specifically, toner information stored in the non-volatile memory can be temporarily stored in random access memories (RAM) installed in image forming apparatuses. When the image forming apparatuses are in operation, toner information stored in the RAMS can be updated as required. Then, only when the image forming apparatuses are set to the power OFF and/or toner replacement, the information stored in the RAMs is written in the non-volatile memories of the IC tags.
Such a method of writing information to the non-volatile memories of the IC tags when image forming apparatuses are set to the power OFF state is disclosed in JP-H11-175411-A. Specifically, a high-capacitance capacitor having a greater capacitance is disposed on a power source line for supplying power to an electrical circuit required for writing information to an IC tag, and a switch is disposed between the capacitor and an internal power source. When the image forming apparatus is set to the power OFF state, the switch is set to the OFF state. As such, the capacitor, which has a capacitance sufficient to function as an auxiliary power source, is provided. The switch is set at the OFF state when the voltage of internal power source becomes low, in which case the voltage of capacitor is applied only to the electrical circuit required for writing information to the IC tag. With such a configuration, a time for writing information to the non-volatile memory in the IC tag can be secured by extending the duration of the fall time of the terminal voltage of capacitor.
However, such integrated circuits generally have an upper limit for fall time of the power voltage supplied to the ICs when the power OFF state is set for the image forming apparatus. As such, although the ICs may be configured to be operated properly when the power voltage supplied to the ICs decreases to a given value within the upper limit for the fall time of the power voltage, if the actual fall time of the power voltage of the ICs exceeds the upper limit of the fall time, the IC tags using such ICs may malfunction.